Connected: An Internet Encyclopedia
RFC 1123 - 3.2.1 Option Negotiation: RFC-854, pp. 2-3

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### 3.2.1 Option Negotiation: RFC-854, pp. 2-3

Every Telnet implementation MUST include option negotiation and subnegotiation machinery [TELNET:2].

A host MUST carefully follow the rules of RFC-854 to avoid option-negotiation loops. A host MUST refuse (i.e, reply WONT/DONT to a DO/WILL) an unsupported option. Option negotiation SHOULD continue to function (even if all requests are refused) throughout the lifetime of a Telnet connection.

If all option negotiations fail, a Telnet implementation MUST default to, and support, an NVT.

DISCUSSION:

  Even though more sophisticated "terminals" and supporting option negotiations are becoming the norm, all implementations must be prepared to support an NVT for any user-server communication.

Next: 3.2.2 Telnet Go-Ahead Function: RFC-854, p. 5, and RFC-858

Connected: An Internet Encyclopedia
RFC 1123 - 3.2.1 Option Negotiation: RFC-854, pp. 2-3